If you're ever in a position where you're sitting and wondering whether or not you need to call or text her again, then it means you need to be spinning more plates i.e. have more girls to be getting with.
Texting or calling...it really doesn't matter if she's into you. If the approach was solid and she's interested, she'll respond either way. If shes not or she's on the fence, it doesn't matter. Now, there HAVE been exceptions to this. I've taken girls who were initially on the fence and gently persuaded them to get over their inhibitions, and finally was able to nail them. Then I realized I wasted a whole bunch of time I should have been using with other conquests.
BUT your time should be more valuable. My advice is don't waste time or energy on chicks that aren't responsive after the approach.
In fact, I prefer using text nowadays to quickly and efficiently weed out the chicks who are not interested enough to get down and dirty in a timely manner. The chicks who made demands, make you wait, think too much about it, etc, are usually just going to drain you of your valuable time and energy (and for most of the guys on here...$$).
In a nutshell: Play the field, make the approaches, get the digits, weed out the flakes and uninterested, and focus on saving your time, money, and energy.